Heavy rockers Disturbed have scrapped their upcoming U.S. tour so frontman David Draiman can undergo treatment for a serious throat condition. The illness is not thought to be permanent, but Draiman has been told he must stop performing for at least four weeks in order for him to fully heal, according to the Boston Globe.

It is not known if Draiman’s condition is linked to his past problems – in 2006 he underwent successful surgery to fix a deviated septum which was making breathing difficult and affecting his vocals.